A simple method for the preparation of bio-inspired nickel bisdiphosphine hydrogen-evolving catalysts

We herein report on a novel, simple and straightforward method for the preparation of nickel bisdiphosphine hydrogen-evolving catalysts, so-called DuBois catalysts, from commercially available nickel hexaaqua salts. This method yields coordination complexes with the same physical characteristics as previously described for compounds prepared from the [Ni(CH3CN)6]2+ precursor. However, if hexaaquanickel(II) chloride is used as a precursor, a different nickel bisdiphosphine complex is formed, which incorporates chloride as an axial ligand. This complex displays a significantly different electrochemical behavior and a diminished activity for proton reduction as compared to classic DuBois catalysts.